Process of and apparatus for dispersing an aeriform body in a liquid body



P 1950 G E HADDELAND ET AL 2,521,215

PROCESS (5F AND APPARATUS FOR DISPERSING AN AERIFORM BODY IN A LIQUIDBODY Filed July 1, 1946 2 Sheets-Sheet l 20 Ame/Mars 6. E. flaw/ land 2.0. J. Kennedy Sept, 5, 1950 Filed Jqly l, 1946 Q G PROCESS OF E.HADDELAND ETAL AND APPARATUS FOR DISPERSING AN AERIFORM BODY IN A LIQUIDBODY 2 Sheets-Sheet 2 GALS. Peg um? TIME 0 o n o e o RATE or uulocla'cuLn-lqu m N RATE 0F GAS ADOOHON IN C'MFT. PER UNI? TI ME I a r 9 l01: l2-

hrwfor$ 6. E. Hadae/and Patented Sept. 5, 1950 UNITED STATES PATENTOFFICE PROCESS OF AND APPARATUS FOR DIS- PER-SING AN AERIFORM BODY IN ALIQUID BODY Canada Application July 1, 1946, Serial No. 680,834

4 Claims. 1

This invention relates to a process of and to apparatus for dispersingan aeriform body in a liquid body and the primary object of theinvention is to provide a simple, easily controlled and economicallyoperable process of and means for effecting the dispersion of anaeriform body, at high rate, into a, liquid body. Another object is i toprovide a process and apparatus, as aforesaid,

by means of which the aeriform body may be introduced at high rate intoa stream of the liquid body with but small depression of the flow rateof the liquid. Still another object is to provide a process andapparatus, as aforesaid, which will serve equally well under conditionsin which the aeriform body is merely dispersed in the liquid or in whichit dissolves in or reacts with the liquid, with or without release ofanother gas and regardless of whether the reaction is exothermic orendothermic. A further object is to provide a process which does notrequire special or expensive apparatus for its carrying out but whichpermits use of ordinary, readily obtainable apparatus. A still furtherobject is to provide a process, as aforesaid, peculiarly adapted fordealing with corrosive bodies, in that the apparatus required is readilyobtainable made of corrosion resisting material. An additional object isto provide apparatus, as aforesaid, in which the gas dispersing meansand its driving means are readily accessible instead of being containedin a closed reaction or other vessel. Various other objects and theadvantages of the invention may be ascertained from the followingdescription and the accompanying drawings.

The term aeriform body is to be understood as including'bodies which aretrue gases or vapours at the temperature prevailing in the process andalso gases or vapours containing finely dispersed droplets of liquid.

It has been proposed to disperse a gas into a liquid by introducing thegas into a stream of the liquid on the intake side of a centrifugalpump, or other liquid circulating means. If the rate of gas input issmall, relative to the rate of liquid circulation, the gas is dispersedin the liquid during passage of the two through the pump. If, however,the rate of gas input is increased beyond a certain value, the flow ofboth gas and liquid becomes erratic and the gas is not well dispersed.If the gas input is still further increased, the pump ceasesto functionin developing pressure and the circulation of the liquid stops.

We have discovered that if suitable pressure is applied to thecirculating liquid on the intake side of the dispersing pump, outwardlyof the point of gas input, the aforesaid limitation on the gas inputrate is very greatly reduced and relatively high gas in-put rates may beused without producing erratic operation and with only slight decreasein the liquid circulating capacity of the dispersion pump. Smoothoperation over a wide range of gas input rate is not disturbed, evenwhen the gas dissolves in or reacts with the liquid and is accompaniedby release of another gas within the dispersing pump.

Broadly speaking, the invention consists, as to process, in circulatinga stream of liquid through a dispersion zone, applying pressure to theliquid stream prior to entering the dispersion zone, and introducing astream of an aeriform body into said liquid stream at a point betweenthe dispersion zone and the point at which pressure is applied to theliquid stream; and consists, as to apparatus, in the combination ofmeans for mechanically dispersing an aeriform body in a stream ofliquid, means for applying pressure to the liquid stream on the intakeside of the dispersing means, and means for introducing the aeriformbody into the liquid stream at a point between the pressure means andthe intake of the dispersing means.

In greater detail, the invention consists in the features andcombinations of features herein disclosed, together with all suchmodifications thereof and substitutions of equivalents therefor as arewithin the scope of the appended claims.

For convenience, in the following description, the aeriform body will bereferred to as gas, but it will be understood that the invention is notthereby limited to true gases.

In the accompanying drawings, which illustrate an embodiment of theinvention now preferred and a modification thereof, but to the detailsof which the invention is not limited:

Fig. 1 is a diagram of apparatus employing a pump for imposing pressureon a liquid stream.

Fig. 2 is a diagram of apparatus adapted to impose pressure on a liquidstream by the action of gravity.

Fig. 3 is a graph illustrating the comparative results of operationswith and without imposition of pressure on the liquid stream. 7

Referring more particularly to the drawings, and especially to Fig. 1thereof, ll designates a storage tank for the liquid in which a gas isto be dispersed, the lower part of which tank is connected by a conduitI2 with the inlet of any suitable sort of pressure applying means l3,such as a centrifugal pump, gear pump or other pump capable ofsubstantially uniform delivery, having any suitabledriving means M, suchas an electric motor. Liquid discharged from the means l3 passes througha conduit 15 to the intake of any suitable sort of means It fordispersing a gas in a liquid, such as a centrifugal pump or an impelleror paddle wheel operating within a casing. having a suitabledrivingmeans H, such as an electric motor. Liquid, with gas dispersedtherein, discharged from the means l6 may flow through a conduit l8leading to the upper part of the tank H. The top of the tank ispreferably closed and provided with an outlet IQ for gas which mayseparate from the liquid. At a suitable point in the conduit IS, a gassupply pipe 20 leads into the conduit. The arrangement may embody merelya simple T-connection of the pipe 20 and the conduit l or the pipe 20may, in effect, extend into the conduit l5, as shown at 2 I, in such away as to produce a. venturi effect giving a negative pressure, orsuction, in the gas line 20. If desired, gas escaping at the tank outletI9 may be conducted to the gas inlet 20 for recirculation. Means 22 and23, which may be heat exchangers or may be simple loops or coils, may beinserted in the conduits l5 and I8, respectively, to provide heating orcooling effect as may be required to promote dispersion of gas in theliquid or to promote reaction of the gas and the liquid or to remove theheat of reaction; or may serve merely to prolong the time of contact ofthe gas and liquid.

In the alternative form of apparatus illustrated in Fig. 2, the tank I Iis located at such elevation above the rest of the apparatus as toprovide a hydraulic head H imposing a pressure on the liquid equivalentto that imposed by the means l3 of Fig. 1. In this form of apparatus,there is inserted in the conduit ill, a closed holding tank 24 and anysuitable sort of liquid raising means 25, such as a centrifugal pump,for raising liquid back to the tank II. The holding tank is providedwith a top vent 26. In this modification the gas supply pipe 20 leadsinto the conduit l2 on the intake side of the dispersing pump l6 and istherefore located between it and the pressure source, as in thepreviously described form.

The preferredcapacity relation of the dispersing means IE to thepressure means I3 or to the hydraulic head H is such that the capacityof the means l6 corresponds, with no gas input, to the delivery capacityof the means I 3 or the capacity of the hydraulic head H to deliverliquid to the means l6. If the capacity of the dispersing means I6 ismaterially greater than as aforesaid, the liquid flow and gas dispersionare irregular and if the capacity is materially smaller, it adds to thefluid flow resistance of the system and consequently decreases the gasdispersing capacity of the system.

The pressure on the inlet side of the dispersing means l6 created by thepressure means l3 or by the hydraulic head H must be sufficient toovercome the fluid friction loss (modified by the input of gas) causedby the venturi 2|, if used, by the dispersing means and conduits,including the heat exchangers or other means 22 and 23.

The advantage of applying pressure to liquid flowing to the dispersingmeans is illustrated by the graph, Fig. 3, which is based on dispersionof air in water, and in which the lower curve shows the relation ofliquid circulation rate to gas input rate when no pressure is applied toliquid entering the dispersing means; while the upper curve shows therelation of these rates when pressure is applied according to thisinvention. In the lower curve, it will be observed, the circulation ratedrops sharply as the gas input rate increases. The portion of the curveshown in broken line indicates erratic flow of gas and liquid and poordispersion of the gas, both increasing with increase in the rate of gasinput, to a point at which flow substantially stops. By comparison, theupper curve shows only a slight drop in circulation rate at a gas inputrate higher than that at which circulation ceases in the lower curve.The upper curve shows the performance of apparatus according to Fig. 1,while the lower curve shows the performance of the same apparatus withthe pressure means short circuited. Dispersion efiiciency using thepressure means l3, as observed visually in a glass section of theconduit l8, showed only a slight decrease but no sharp break until theflow friction became greater than the maximum discharge pressure of thedispersing pump.

When circulation is not required, that is, when the liquid need passthrough the dispersing zone only once, the apparatus may be modified byelimination of the conduit ill of Fig. 1 and the elimination of theholding tank 24, the liquid raising means 25 and the conduit l8 of Fig.2.

The process of this invention is applicable to gases and liquids havingdensities and viscosities within a wide range and may be used incarrying out a great variety of physical and chemical processes.

Having thus described our invention, we claim:

1. Apparatus for dispersing an aeriform body in a liquid body, whichapparatus comprises a conducting system for a stream of liquid,including a centrifugal pump, aconduit for conveying the liquid streamto the centrifugal pump, means for applying pressure to the liquid insaid conduit, thereby to maintain a flowing stream of liquid, and asupply pipe for introducing the aeriform body to said conduit at apressure greater than the positive pressure applied to the liquid, saidsupply pipe being connected to the said conduit between the pump and thesaid means for applying positive pressure to the liquid.

2. Apparatus according to claim 1 in which the pressure applying meansis a pumping means;

3. Apparatus according to claim 1 in which the pressure applying meansis a part of the conducting system leading to the intake of thecentrifugal pump, disposed at such elevation above the centrifugal pumpas to establish a column of the liquid sufiicient to apply pressure inexcess of the pressure drop in the system due to friction and to theintroduction of the aeriform body.

4. In a method of dispersing an aeriform body in a liquid body bypassing the two together through a centrifugal pump, the steps ofapplying positive pressure to a stream of the liquid only on the inletside of the pump, introducing the aeriform body into the stream of theliquid body at a point between the pump and the point of application ofsaid positive pressure to the liquid and at a pressure greater than theposi tive pressure applied to the liquid, and discharging the resultantdispersion at a pressure lower than said positive pressure applied tothe liquid.

GEORGE ERLING HADDELAND. DOUGLAS JOSEPH KENNEDY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,740,441 Chogo Dec. 24, 19291,808,956 Ketterer June 9, 1931 1,917,577 Doble, Jr. July 11, 19332,020,850 Myhren et al Nov. 12, 1935 2,151,547 Auerbach Mar. 21, 1939

